Greenwire (08/02/2011) Phil Taylor, E&E reporter
The United States can minimize the risk of severe wildfires in dry Western forests by thinning them to no more than 100 trees per acre, according to a new Forest Service study.
The study, published in the Canadian Journal of Forest Research, is the largest of its kind and provides a scientific blueprint for reducing tree densities and surface fuels, which are largely to blame for massive wildfires this year in Arizona and New Mexico, the worst ever for both states, the agency said.
The study explored the likely impacts of various thinning levels on the potential for crown fires, a particularly deadly and unpredictable type of wildfire that burns into the canopies of trees.
Computer simulations of more than 45,000 stands of ponderosa pine and Douglas fir in 11 Western states found that densities of between 50 and 100 trees per acre would minimize the risk of crown fires. The study also considered densities of 300 and 200 trees per acre.
Intensive thinning, combined with the removal of post-treatment "slash" debris, both reduces the risk of initiating a crown fire and blocks their spread, the study concluded.
"This study proves once again that an ounce of prevention equals a pound of cure," Forest Service Chief Tom Tidwell said in a statement. "Thinning dense forests reduces the impacts of the catastrophic wildfires we've already seen this year and expect to see more and more of in the future."
The research will help forest managers protect communities that abut forests while providing timber harvest jobs and promoting better forest health, Tidwell said.
The study comes on the heels of the massive Wallow fire in Arizona, which burned more than 538,000 acres but claimed only 38 structures thanks in part to a collaborative forest restoration project that had previously treated some 35,000 acres.
The White Mountains stewardship contract, part of the "Four Forests" collaborative in the Apache-Sitgreaves, Kaibab, Coconino and Tonto national forests, seeks to restore up to 150,000 acres of degraded forest over 10 years by strategically thinning small trees in overgrown ponderosa forests.
The thinning allowed firefighters to halt the fire's spread in many areas and protect thousands of structures, according to the Forest Service.
Thinning is also credited for providing a buffer to a separate fire this summer around the city of Los Alamos, N.M., which is home to a sprawling federal nuclear weapons lab, officials have said (Land Letter, July 7).
"Our findings now give a sense of just how much thinning is required," said Morris Johnson, a Forest Service fire ecologist and lead author of the study. "We found that thinning at this level reduced tree density, raised the canopy base height and reduced canopy density."
The Forest Service, which manages nearly 200 million acres of forests, last year treated more than 2 million acres for hazardous fuels reduction, mostly near communities in the wildland-urban interface. The agency had already treated 900,000 acres by mid-June, Tidwell said.
Lawmakers in Arizona and New Mexico have recently introduced legislation that would expedite the removal of hazardous, dead and dying trees surrounding communities near the Wallow fire area.
The bill, S. 1344, by Arizona Republican Sens. Jon Kyl and John McCain, would direct the Forest Service to identify forested areas near residences where dead or fire-prone trees could be harvested to spur economic development and gird forests to withstand future fires. It will receive a hearing tomorrow before the Senate Energy and Natural Resources Committee (E&E Daily, Aug. 1).
Similar legislation has been introduced in the House by Reps. Steve Pearce (R-N.M.), Paul Gosar (R-Ariz.) and Jeff Flake (R-Ariz.).
"We must reevaluate our forest management policies at all levels of government because the status quo is detrimental to our region's ecological health, our safety and our local and national economy," Gosar said in a statement today. "The recent fires, some of the largest forest fires in recorded history, simply add further urgency to this work."
From:
Caitlin Sause
Government Relations Advisor
t 503.944.6117
f 503.295.1058
csause@balljanik.com
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